Maybe she just got tired of always being the strong one in family.
I think that statement tells where the root of the problem began. If you do go back home, you need to be determined that you will be the strong one in the family. A woman naturally leans on her H b/c he is the leader, the protector, and the provider. It doesn't mean that she can't be strong and have a career, etc., but it's the way she was made.
I think somewhere along the way you forgot this. You would not be the first young father who felt that his W did not have time for him. It is an exhausting job to have two small children, a H, and a job.
You have a difficult decision to make. If you go home and have no income, then that could place you in a weaker position. OTOH, your family is more important than anything else.
It could be that your W was suffering from some depression of her own and the email kind of helped to push her away, IDK. However, if you go home and show her the man she fell in love with, that could change real fast.
Here's the thing, how will you ever know if she was discouraged.....or involved with somebody else, unless you go home to find out?
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
